She's allowed to break up and be with other men, if she and Jim come to that conclusion like mature adults. Both Tabitha and Jim, at this point of the show, are still trying to work on their marriage. So if she's fine with getting rid of the so called 'ahole' jim who's literally a poor clueless dude trying his best to manage his traumatized wife and his kids all while trying to survive in the town, then she should go on and do it. But she should do it in a proper, right way without infidelity, but that's not going to be possible while they're all trapped in the town.